This invention relates to mainly a nozzle for gun type burner to spray and burn fuel oil fed under pressure by a pump.
Such gun type burners have hitherto been generally widely used because of their good firing and quenching properties and stable quantity of combustion. However, the quantity of combustion which is different depending upon the quantity of heat required with every uses has come to be required for economy of energy. On the other hand, since the gun type burners are considerably stable in quantity of combustion because of pressure spraying type, the control of quantity of fuel oil sprayed from one and the same nozzle was extremely difficult.
The standard pressure applied for spraying fuel oil from the gun type burner is generally 7 kg f/cm.sup.2 (100 PSI). Taking the case of a nozzle of 1 G pH, the quantity of fuel oil sprayed at a pressure of 7 kg f/cm.sup.2 is approximately 3.78 l/H. The quantity sprayed at half the pressure is 2.6 l/H, which means that 50% change in pressure causes only 30% change in quantity of spray, and the decrease in spraying pressure resulted in coarse particles sprayed and consequently extremely worse state of combustion. Thus the control process of decreasing the pressure of fuel oil could not be used practically.
Moreover, there was the use of a return nozzle for a method of changing the quantity of combustion without changing the pressure of a pressure pump.
Such method comprising returning a portion of fuel oil under pressure from a nozzle, permits only two step change-over of the quantity of combustion and requires a proportional control valve to perform the proportional control. With use of the expensive return nozzle and proportional control valve, the system for carrying out such method became considerably expensive as a control system, and therefore had no marketability and could not continue to exist as commodities. Eventually, the control of the gun type burner has been performed depending upon ON-OFF control from an aspect of cost.